1. Field of the Invention
The present invention relates, in general, to an arrowhead having expanding blades capable of being retracted or expanded by a gear mechanism, and, more particularly, to an arrowhead in which a rack gear formed on a shaft is engaged with pinion gears of expanding blades coupled to a main body, and thus a relative movement between the main body and the shaft causes the retraction or expansion of the expanding blades.
2. Description of the Related Art
Generally, an arrow is composed of a hollow arrow shaft, an arrowhead attached to a leading end of the arrow shaft, the nock of an arrow using which the arrow is fit in the string, and feathering for securing the flight stability of an arrow.
The arrowhead serves to pass through a target, so it should have excellent wear resistance and strength and it should have a structure enabling its flight to be stable, because upon hitting the target, the accumulated energy of an arrow is collected upon the arrowhead.
Generally, an arrowhead has a sharpened tip to improve penetration, but such a sharpened arrowhead is not practical for certain types of hunting. This is because it is difficult for the sharpened arrowhead to kill large game and thus gain control over the same. Thus, for this reason, a broad type arrowhead which has two to four sharp blades on its edge to induce profuse bleeding and the death of game may be used.
There is also disclosed a variety of arrowheads in which the blades are normally retracted inside the arrowhead and expand upon hitting a target because the blades of the broad type arrowhead affect the flight stability of an arrow.
Such blades having an expandable structure are referred to as expanding blades. A variety of conventional examples of arrowheads having such expanding blades are disclosed in U.S. Pat. No. 5,082,292 entitled “BROADHEAD WITH DEPLOYABLE CUTTING BLADES,” U.S. Pat. No. 5,066,021 entitled “ARROW SYSTEM,” U.S. Pat. No. 4,973,060 entitled “ARROHEAD WITH EXPANDABLE BLADES,” U.S. Pat. No. 6,669,586 entitled “EXPANDING BROADHEAD,” U.S. Pat. No. 6,258,000 entitled “PENETRATION ENHANCING AERODYNAMICALLY FAVORABLE ARROWHEAD,” U.S. Pat. No. 6,287,223 entitled “DULLING PREVENTION FOR SHARP CUTTING EDGE OF BLADE-OPENING ARROWHEAD BLADES WHEN IN A CLOSED IN-FLIGHT POSITION,” U.S. Pat. No. 8,062,155 entitled “ARROWHEAD HAVING BOTH FIXED AND MECHANICALLY EXPANDABLE BLADES,” and U.S. Pat. No. 6,200,237 entitled “SLIDING BODY EXPANDING BROADHEAD,” respectively.
All of the patent documents described above disclose an arrowhead having two to four expanding blades, in which, when an arrow hits a target, such as game, a plurality of expanding blades are expanded to enlarge and more deeply penetrate into the wound of the game, thereby enhancing the killing capability of the arrow.
However, such conventional expanding blades have a problem in that, when an arrow is flying after being shot, the expanding blades expand by themselves, thereby degrading the flight stability of the arrow and adversely affecting the hit rate and flight distance of the arrow.
Due to such a problem, in the case of an arrowhead having the conventional expanding blades, the plurality of expanding blades must be typically retracted and grouped together before an arrow is shot, and then be tied by a band or string which can be easily broken or slip off when the arrow hits the target.
In doing so, the expanding blades are maintained in a retracted state during flight of the arrow, but can be expanded by slipping-off of the band or string as soon as the arrow hits and penetrates into the target.
However, in such a manner in which the expanding blades should be retracted and then tied or bundled by the band and the like, there are inconveniences in that the retracted expanding blades must be bundled by the band and the like whenever an arrow is shot, and in turn the band must be always carried when hunting.
Therefore, there is a need to develop an arrowhead in which, during flight of an arrow, retracted expanding blades can be kept un-expanded to ensure the flight stability without using an additional means, and the expanding blades can automatically expand only when the arrow hits and penetrates into a target.
Documents of Related Art    U.S. Pat. No. 5,082,292 entitled “BROADHEAD WITH DEPLOYABLE CUTTING BLADES”;    U.S. Pat. No. 5,066,021 entitled “ARROW SYSTEM”;    U.S. Pat. No. 4,973,060 entitled “ARROHEAD WITH EXPANDABLE BLADES”;    U.S. Pat. No. 6,669,586 entitled “EXPANDING BROADHEAD”;    U.S. Pat. No. 6,258,000 entitled “PENETRATION ENHANCING AERODYNAMICALLY FAVORABLE ARROWHEAD”;    U.S. Pat. No. 6,287,223 entitled “DULLING PREVENTION FOR SHARP CUTTING EDGE OF BLADE-OPENING ARROWHEAD BLADES WHEN IN A CLOSED IN-FLIGHT POSITION”;    U.S. Pat. No. 8,062,155 entitled “ARROWHEAD HAVING BOTH FIXED AND MECHANICALLY EXPANDABLE BLADES”; and    U.S. Pat. No. 6,200,237 entitled “SLIDING BODY EXPANDING BROADHEAD.”